Valve and method for operating mechanical tuyere puncher and the like



Feb. 6-, 1968 A. c. MAGEE ET AL 3,367,238

VALVE AND METHOD FOR OPERATING MECHANICAL TUYERE PUNCHER AND THE LIKE 4 Filed Sept. 15, 1964 2 Sheets-Sheetl 8 fV/MUSI Feb. 6, 1968 c, MAGEE ET AL 3,367,238

VALVE AND METHOD FOR OPERATING MECHANICAL TUYERE PUNCHER AND THE LIKE Filed Sept. 15, 1964 2 Sheets-Sheet 2 4485 Owens/7965: (/4 765 M94 6 4355 United States Patent Ofiice 3,367,238 Patented Feb. 6, 1968 $01, 15 Claims. (Cl. 91-36) ABSTRACT OF THE DISCLOSURE A spool valve which is individually mounted on a single stroke fluid motor and a valve arrangement which comprises a plurality of spool valves individually mounted on single stroke fluid motors are disclosed. The spool valve is constructed so that in the actuated position Working fluid enters the valve to fire the associated motor whereupon the valve is reset and Working fluid is then conducted through the reset valve to the next actuated valve in the series to fire the associated motor. The valve arrangement comprises means for transferring working fluid from one valve to the next valve in the series and a control system to automatically and substantially simultaneously actuate all of the valves in the series.

The present invention relates to apparatus and method for controlling the operation of fluid motors, and more particularly to a valve arrangement for automatically operating fluid motors used as tuyere punchers to remove obstructions in the tuyeres of metallurgical converters.

Metallurgical converting is a process of refining metals wherein air or oxygen-containing gases are blown into a molten bath. The oxygen in the air or other oxygen-containing gases employed ultimately preferentially reacts with the impurities in the bath and the impurities are removed either as a slag or as a gas. Metallurgical converters have generally taken the form of a crucible furnace with passages known as tuyeres located below the level of the molten charge to admit the oxygen-containing gases under pressure. Although the oxygen ultimately reacts with the impurities desired to be eliminated, the oxygen may react with materials in the immediate vicinity of the tuyeres forming accretions in and/or around the tuyeres thus hindering the flow of treating gases to the molten charge. In the past, these accretions were removed or dislodged by manually pushing or punching a metallic bar through the tuyere in a reciprocating manner. Not only was the job of punching tuyeres expensive in terms of labor but the job also presented very disagreeable and hazardous working conditions.

It has been proposed to equip the tuyeres of metallurgical converters with mechanical tuyere punchers to remove obstructions in the tuyeres. Mechanical tuyere punchers have generally been of the form of piston and cylinder fluid-driven reciprocating motors with a punch red attached to the motor piston and extending through the tuyere at the forward end of the stroke. Canadian Patent No. 557,354 illustrates a general arrangement of a mechanical tuyere puncher on a metallurgical converter.

The operation of the tuyere puncher in the abovementioned patent consists in admitting working fluid, usually compressed air, into a valve on the motor. When the valve is cocked, the working air enters the rearward portion of the motor which drives the motor piston and punching rod forward to punch the tuyere. The kinetic energy of the piston compresses the fluid medium, e.g., air, ahead of the piston to an extent which is sufficient to return the motor piston to its at-rest position. As the motor piston approaches the end of its forward stroke, a portion of the compressed medium ahead of the piston in the working cylinder is directed to the forward portion of the valve to return the valve to its at-rest posidon. The valve in its at-rest position opens an exhaust port and permits the spent working air to be exhausted from the rearward portion of the motor as the piston is being returned by the compressed air in the motor cylinder ahead of the motor piston. When the motor piston is at rest, the motor-valve arrangement may then be set or cocked so that the working piston can be fired again.

As can be seen from the above description, the valve on the motor assumes an important role in controlling the operation of the working motor. Attempts have been made to provide valves to control the mechanical punching of tuyeres when using fluid motors. The prior art valves have presented numerous difficulties. For example, some valves have had a great number of moving parts which not only increases the initial cost but presents great problems in maintenance. Other prior art valves utilized a sliding-valve feature which because of rnetal-to-metal con tact under the pressure of the working medium resulted in wear of the valve moving parts and attendant short life of the valves. Another disadvantage of prior art valves was that the design necessitated numerous passages which changed directions very sharply and when operating a series of motors this is undesirable because large pressure drops in the working fluid would have to be remedied by introduction of working fluid at many stations. Although attempts were made to overcome the foregoing difficulties and other disadvantages, none, as far as we are aware, was entirely successful when carried into practice commercially on an industrial scale.

It has now been discovered that a series of fluid motors each equipped with a simplified spool valve can be automatically operated.

It is an object of the present invention to provide a valve arrangement to permit automatic operation of a series of fluid motors.

Another object of the invention is to provide a simplified spool valve with a minimum number of parts.

The invention also contemplates providing an arrangement of valves and fluid motors in series in which the working fluid pressure drop from one motor to another is held to a minimum.

It is a further object of the invention to provide a simplified valve which is relatively inexpensive and is easy to construct and maintain.

The invention further contemplates providing a valve arrangement to permit automated operation of a series of fluid motors.

It is another object of the invention to provide a method of operating a series of fluid motors to punch blocked tuyeres of metallurgical converters.

Still another object of the invention is to provide a method of operating a series of fluid motors in which partial firings or misfirings are avoided.

Other objects and advantages will become apparent from the following description taken in conjunction with the accompanying drawing in which:

FIGURE 1 is a longitudinal cross-sectional view of a novel valve of this invention operably affixed to a fluid motor;

FIGURE 2 depicts a cross-sectional plan view of a valve of this invention;

FIGURE 3 shows a front end view of a valve of this invention in combination with a fluid motor; and

FIGURE 4 illustrates in a diagrammatic drawing an arrangement for automating a series of valve-motor combinations.

Generally speaking, the present invention contemplates a novel spool valve mechanism for controlling a fluidpowered reciprocating tuyere puncher motor and a method for controlling the operation of a bank of such tuyere puncher motors connected in series. The valve comprises the combination of a valve chest with at least four fluid ports in the walls thereof and a spool-like member having a plurality of flanges in fixed longitudinal relation to each other disposed therein with said flanges being substantially engaging with the valve chest walls and in slidable contact therewith to form therewith a plurality of chambers movable longitudinally in forward and rearward directions, i.e., in the forward and at-rest positions of the spool-like member, within the valve chest.

Generally, for simplicity in construction, the valve chest cross section is circular although it may take other geometric forms, e.g., elliptical, rectangular, triangular, etc., in response to particular requirements. The ports provide entry and exit means for the working fluid, an exhaust means for the spent working fluid from the motor and communication means to the motor to permit working fluid to be introduced and subsequently exhausted therefrom. When the spool-like member is in the forward or cocked position, the flanges form fluid-tight chambers so that the exhaust port is isolated, the working fluid inlet port and motor access port are in communication and the working fluid outlet port is isolated. In the rearward or at-rest position the flanges on the spool-like member form fluid-tight chambers so that the exhaust port and motor access port are in communication and the working fluid inlet port and working fluid outlet port are in communication. Means are provided to move the spoollike member to the forward position. Means are also provided for moving the spool-like member to the rearward position.

When operation of a series of fluid motors is contemplated, the working fluid inlet of the valve on the first motor is connected with a source of high pressure fluid and the working fluid outlet is connected with the working fluid inlet of the valve on the second motor. This arrangement is repeated for each succeeding motor. The working fluid outlet of the valve on the last motor is connected to means that permit the exhausting from all the valves of the high pressure working fluid.

The operation of the motors is started by activating the means for moving the spool-like member forward in all of the valves. High pressure working fluid, e.g., air, is then permitted to flow through the first motor, thereby driving forward the working piston therein to punch the tuyere associated therewith. When the piston of the first motor is substantially near the end of its working stroke,

the means for moving the spool-like member of the first valve to the rearward position is actuated. The rearward position of the spool-like member permits the high pressure working fluid to enter the second valve. This process is repeated for each succeeding valve-motor arrangement. When the last motor of the series is fired, the source of the high pressure working fluid is turned oif and the exhaust means connected to the valve on the last motor as actuated to exhaust all of the valve chests of residual high pressure working fluid. When all the valve chests are exhausted, the means controlling the exhaust are deactivated and the entire process can be repeated.

Reference to the drawings will enable one skilled in the art to better understand the present invention. Turning now to FIGURES l, 2 and 3 in the drawing, reference character 1 depicts a pneumatic motor, which forms no part of the invention, operably connected with the valve arrangement 2 of this invention. Valve body 3 is provided with end plates 4 and 5 fastened to the valve body by bolts 6. In an advantageous embodiment, the valve body is lined with a tubular steel liner as indicated at 7. The valve chest has a number of of ports as shown at 8, 9, and 11. Spool-like member 12 is longitudinal-1y disposed in the valve chest. The spoollike member is movable to a rearward position, as shown by the solid lines in FIG. 1, and a forward position, as shown by the dotted lines. The spool-like member, as shown in this embodiment, has three flanges 13, 14 and 15, each of which has O-ring seals 16, 17 and 18 to form air-tight chambers with the valve chest Walls. Flange 13, in this embodiment, is dimensioned to block off or isolate the exhaust port 8 when the spool-like member is in the forward or cocked position and high pressure working air is admitted to the valve which avoids the necessity of an additional flange. Valve chest 3 has ports 19 and 20 which are the means of this embodiment to provide forward and rearward motion of the spool-like member. The interrelationship of the ports 8, 9, 10, 11, 19 and 20 and the chambers formed by the flanges 13, 14 and 15 and the valve chest walls can best be seen by analyzing the operation of the valve. Assuming the valve 2 is in at-rest position shown by the solid lines, high pressure actuating air is admitted to port 19 of each valve which causes the spool-like member to move to the forward or cocked position. The chamber formed by end wall 5 and the back face of the flange 13 is then exhausted of the high pressure air. In the cocked position flange 13 covers and thus closes the exhaust port 8. High pressure working air entering port 10 is conducted through port 9 to the pneumatic motor via motor passage 22 to start the motor piston 23 on its working stroke. As the motor piston 23 advances, the air in front of the piston is compressed. This compressed air is directed to port 20 through motor passage 24 and moves the spool-like member to the rearward or at-rest position at which position exhaust port 8 is open to the atmosphere and spent working air behind motor piston 23 conducted through motor passage 22 is exhausted as motor piston 23 is returned to its at-rest position. A bleeder port 32 is located in flange 15 of the spool-like member. This port provides communication from the chamber formed by flanges 14 and 15 of the spool-like member and the walls of the valve chest to the pneumatic motor cylinder 21 via port 20 and motor passage 24. Thus, when the spool-like member is in the rearward position, high pressure air may pass from port 10 through bleeder ports 32, port 20 and motor passage 24 to pneumatic motor cylinder 21, thus pressuring said cylinder 21 and insuring that motor piston 23 and spool-like member 12 is maintained in the at-rest or rearward porition. Only in the at-rest position can the high pressure working air entering through working air inlet 10 be conducted through port 11 to the working air inlet of the next motor having its valve in the cocked position. Since no sharp changes of direction or long distances of travel are present, the magnitude of the pressure drop, if any, will be reduced. After the last motor in the series is actuated and operation of the series of valve-motor combinations is to be repeated, the high pressure working air is turned off and all the valves are exhausted since the series of valve chambers formed by flanges 14 and 15 and the valve walls are all in communication. After all the valves have been exhausted, the working cycle can then be repeated.

The motor-valve arrangement for the operation of a series of motors is diagrammatically illustrated in FIG. 4. The pneumatic motors are represented generally at 1 and the valves at 2. The working air inlet 10 of the first valve is operably connected to a control means 26 which controls the flow of high pressure working air from a source not shown. The working air outlet 11 of the first valve is connected to the working air inlet 10 of the second valve. This pattern is repeated for each valve in the series. The working air outlet 11 of the last motor in the series is operably connected to control means 27 which permits exhausting residual high pressure working air after all the motors have completed their working stroke. Ports 19 of all the valves are connected to a header 30 which leads to a source of high pressure actuating or cocking air. The header 30 has control means 28 and 29. Control means 28 operate to open or close header 30 to the atmosphere. Control means 29 open and close header 30 to a high pressure actuating air source not shown in the drawing.

Control means 26, 27, 28 and 29 may be solenoid switches which control valves not shown in the drawing. The solenoid switches are energized and de-energized by a timer 31. The timer 31 is energized by a remote signal which may be generated by a change in working conditions, e.g., a drop in the volume of air flowing to the converter as a result of buildup of accretions in the tuyeres, or the passage of a predetermined interval.

In practicing our invention when blowing a nickelcopper matte, two banks of motors are advantageously used, each bank having a series of motors equal to onehalf the number of tuyeres in the converter. Each motor can be arranged on a tuyere as shown by Canadian Patent No. 557,354. When, as in the general case, a tiltable converter is being utilized, the source of high pressure working fluid is left open to the spool valves to maintain the spool-like members and the motor pistons in the atrest position when tilting the converter to charge or discharge. Keeping the valves open to the source of high pressure working fluid insures that the motor pistons 23 along with the associated punch rods are maintained in the at-rest position since the high pressure working air entering the motor cylinder 21 through bleeder port 32, motor port 20 and motor passage 24 exerts enough pressure against motor piston 23 and spool-like member 12 to prevent their forward movement as the converter is being tilted. After the converter has been charged and blowing has been commenced, the operation of each bank of fluid motors, with particular reference to FIG. 4, is sequentially as follows:

(1) Remote signal starts timer 31,

(2) timer 31 energizes control means 26 to close high pressure working air to valves 2,

(3) the timer then energizes control means 27 to exhaust residual high pressure working air from the valves 2,

(4) the timer energizes control means 28 to close header 30 to the atmosphere,

(5 the timer energizes control means 29 to open header 30 to high pressure actuating air to substantially simultaneously actuate all the valves,

(6) the timer de-energizes control means 29 to close header 30 to high pressure air,

(7) the timer de-energizes control means 28 to open header 30 to atmosphere,

(8) the timer de-energizes control means 27 to close valves 2 to the atmosphere,

(9) the timer de-energizes control means 26 to open the valves 2 to high pressure working air to fire the motors, and

(10) after all of the motors in the bank have fired sequentially, the timer is set to receive another remote signal to repeat the operation.

Although the foregoing description showed the operation of the valves when using air, it is to be understood that any compressible fluid may be used. Accordingly, the word fluid in the present application refers to any compressible fluid. Examples of other useful fluids are steam, inert gases and compressible hydrocarbons.

The present invention is particularly applicable to tuyere punching operations as outlined hereinbefore, where it is desirable to maintain large volume flows of air or oxygen-containing gases to a molten charge. The frequency of the cycle of operations can be regulated so as to give a desired flow rate. Although the cycle can be regulated by flow rate measurements, it has been found advantageous to operate on a predetermined time interval. This time interval will vary depending on the composition of the molten charge. For example, a time cycle of about thirty seconds to two minutes has been found satisfactory with the lower time cycles being advantageous when blowing a nickel-copper matte.

Although the operation of fluid motors equipped with the novel valve arrangement of this invention has been illustrated with reference to punching tuyeres of a metallurgical converter, it is to be noted that a series of motors so equipped could be used in metal punching or stamping operations. This is particularly true where operation requires maximum power of each motor since each motor fires individually and there is no sudden drop in pressure along the series.

It is to be observed that the present invention provides simplified valves for controlling the operation of a series of fluid motors. When using a series of fluid motors equipped with the valves of this invention, no sudden drop in working fluid pressure is experienced since the motors fire one at a time in rapid succession.

Furthermore, the invention provides a control system in which only one set of four controls is required to operate an entire bank of motors. This not only reduces initial cost but also reduces maintenance expenses.

Moreover, the invention provides a method of operating a series of motors which is particularly useful in tuyere punching of metallurgical converters.

Although the present invention has been described in conjunction with preferred embodiments, it is to be understood that modifications and variations may be resorted to without departing from the spirit and scope of the invention, as those skilled in the art will readily understand. Such modifications and variations are considered to be within the purview and scope of the invention and appended claims.

We claim:

1. A valve arrangement comprising, in combination, a plurality of series-connected, cockable, re-settable spool-type valves individually mounted on and operatively connected to fire in sequence single stroke fluid motors, header means having fluid-admitting and fluidexhausting means connected to said valves to communicate cocking fluid thereto and to exhaust cocking fluid therefrom, means for providing working fluid to and exhausting working fluid from said valves, re-setting means connected to each of said valves and control means for admitting cocking fluid and working fluid to and exhausting cocking fluid and working fluid from said valves, with each of said valves being constructed such that, in the cocked position of the valve, Working fluid is admitted to the motor associated therewith to fire said motor whereafter the valve mounted on said motor is re-set and such that, in the re-set position, working fluid is communicated through the valve to the next successive valve in the series and the motor associated with the valve is exhausted of working fluid, whereby each of said valves is cocked substantially simultaneously, working fluid is admitted thereafter to fire each motor in sequence, each valve is re-set in sequence, working fluid is then exhausted from each motor in sequence, working fluid is thereafter exhausted from all of said valves, whereafter the cycle can be repeated as directed by said control means.

2. A valve arrangement as described in claim 1 wherein said control means are valves controlled by solenoid switches.

3. A valve arrangement as described in claim 1 wherein said control means are energized by a timer.

4. A process for sequentially operating a series valve arrangement with each valve individually mounted on a single stroke fluid motor comprising the steps of substantially simultaneously actuating all of the valves by admitting actuating fluid to the valves, thereafter exhausting the actuating fluid to the atmosphere, then admitting working fluid from a working fluid source to the first valve in the series to fire the first motor, then resetting said first valve, conducting working fluid from said first valve to the next valve in the series to fire the motor associated therewith, sequentially repeating the step of admitting working fluid to a valve in the series to fire the motor associated therewith and to re-set the valve for each valve in the series, and closing the working fluid source to the first valve in the series after the motor associated with the last valve has fired.

5. A process as claimed in claim 4 in which after closing the source of working fluid all the valves are ex hausted of residual working fluid.

6. A valve in combination with a fluid motor to be operated in a series valve arrangement in which each valve is individually mounted on a single stroke fluid motor comprising means defining an elongated valve chest, said valve chest having a plurality of fluid passage means, actuating means and resetting means, said passage means defining an exhaust outlet, a motor port, a working fluid inlet and a working fluid outlet, a spool-like member disposed longitudinally in said valve chest, said spool-like member having a plurality of flanges and being movable to a forward position by said actuating means and to a rearward position by said re-setting means, and said plurality of flanges forming substantially fluid-tight chambers with the walls of said valve chest so that in said forward position the exhaust outlet is isolated, the motor port and working fluid inlet are in communication and the working fluid outlet is isolated and so that in said rearward position the exhaust outlet and motor port are in communication and the working fluid inlet and working fluid outlet are in communication.

7. A valve as claimed in claim 6 wherein the actuating means is a fluid port and fluid entering said port acts against the rearward flange of the spool-like member to move said member to the forward position.

8. A valve as claimed in claim 6 when operably attached to a fluid motor wherein said re-setting means is a fluid passage leading to the forward end of the motor so that fluid compressed by the working stroke of the motor passes through said fluid passage and acts on the forward flange of the spool-like member to move the spool-1ike member to the rearward position.

9. A valve as claimed in claim 6 wherein the valve chest has a steel liner.

10. A valve in combination with a fluid motor to be used in a valve series arrangement in which each valve is individually mounted on a single stroke fluid motor C0111- prising means defining an elongated valve chest, said valve chest having fluid passage means defining an actuating fluid inlet, an exhaust outlet, a motor port, a working fluid inlet, a working fluid outlet and a re-setting fluid inlet, a spool-like member mounted longitudinally in said valve chest, said spool-like member having a plurality of flanges and being movable to a forward position by action of actuating fluid and to a rearward position by action of re-setting fluid and said plurality of flanges forming substantially fluid-tight chambers with the walls of said valve chest so that in the forward position the exhaust outlet is isolated, the motor port and working fluid inlet are in communication and the working fluid outlet is isolated and so that in the rearward position the exhaust outlet and motor port are in communication and the working fluid inlet and working fluid outlet are in communication.

11. A valve in combination with a single stroke reciprocating motor comprising means defining an elongated valve chest, said valve chest having fluid passage means defining an actuating fluid inlet, an exhaust outlet, a motor port, a working fluid inlet, a working fluid outlet and a re-setting fluid inlet, a spool-like member longitudinally disposed within said valve chest and movable to forward and rearward positions, said spool-like member having a plurality of flanges which form a plurality of fluid-tight chambers with the walls of said valve chest, one of said flanges having a bleeder port which provides communication between the working fluid inlet and the re-setting fluid inlet when said spool-like member is in the rearward position, and said valve being operably connected to a single stroke fluid motor such that actuating fluid entering the actuating fluid inlet moves the spool-like member to the forward position thereby isolating the exhaust outlet, bringing the motor port and working fluid inlet into com- 'munication to start the motor piston on its working stroke and isolating the working fluid outlet and such that fluid compressed by the motor piston returns the-motor piston and the spool-like member to their rearward positions thereoy bringing the exhaust outlet and motor port into communication, and bringing the working fluid inlet into communication with the working fluid outlet and the resetting fluid inlet whereby working fluid passes through the bleeder port to and through the re-setting fluid inlet to maintain the motor piston and the spool-like member in the rearward position.

12. A valve in combination with a single stroke reciprocating motor comprising means defining an elongated valve chest, said valve chest having fluid passage means defining an actuating fluid inlet, an exhaust outlet, a motor port, a working fluid inlet, a working fluid outlet and a re-setting fluid inlet and a spool-like member longitudinally disposed within said valve chest and movable to forward and rearward positions, said spool-like memberhaving a plurality of flanges which form a plurality of fluid-tight chambers with the walls of said valve chest, and said valve being operably conected to a single stroke fluid motor such that actuating fluid entering the actuating fluid inlet moves the spool-like member to the forward position thereby isolating the exhaust outlet, bringing the motor port and working fluid inlet into communication to start the motor piston on its working stroke and isolating the working fluid outlet and such that fluid compressed by the motor piston returns the motor piston and the spool-like member to the rearward position thereby bringing the exhaust outlet and motor port into communication, and bringing the working fluid inlet into communication with the working fluid outlet.

13. A valve in combination with a single stroke reciprocating motor comprising means defining an elongated valve chest, said valve chest having fluid passage means defining an exhaust outlet, a motor port, a working fluid inlet, and a working fluid outlet, a spool-like member longitudinally disposed within said valve chest and movable to forward and rearward positions, said spool-like member having a plurality of flanges which form a plurality of fluid-type chambers with the walls of said valve chest, actuating means to move said spool-like member to said forward position, and re-setting means to move said spool-like member to said rearward position, said valve being operably connected to a single stroke fluid motor such that said actuating means move the spool-like member to said forward position to isolate the exhaust outlet, to bring the motor port and working fluid inlet into communication to start the motor piston on its working stroke and to isolate the working fluid outlet and such that said re'setting means return said spool-like member to said rearward position to bring the exhaust outlet and motor port into communication and to bring the working fluid inlet into communication with the work ing fluid outlet.

14. A valve in combination with a single stroke reciprocating motor as described in claim 13 arranged in series with at least one additional valve-motor combination which comprises means for conducting working fluid from the working fluid outlet of each valve in the series to the working fluid inlet of the next valve in the series such that working fluid introduced to the working fluid inlet of the first valve of the series with its spool-like member in the forward position starts the motor piston on its working stroke and such that when the spool-like member is moved to the rearward position by the re-setting means working fluid is then conducted through the working fluid outlet of the first valve in the series to the working fluid inlet of the next valve in the series to fire the motors sequentially.

15. A valve arrangement comprising, in combination, a plurality of series-connected valves individually mounted on and operably connected to fire in sequence single stroke fluid motors; each of said valves comprising means defining an elongated valve chest, said valve chest having a plurality of fluid passage means defining an actuating fluid inlet, an exhaust outlet, a motor port, a working fluid inlet, a working fluid outlet and a re-setting fluid inlet, a spool-like member mounted longitudinally in said valve chest, said spool-like member having a plurality of flanges and being movable to an actuated position by action of actuating fluid and to a re-set position by action of re-setting fluid, and said plurality of flanges forming substantialy fluid-tight chambers with the wall of said valve chest so that in the actuated position the exhaust outlet is isolated, the motor port and working fluid inlet are in communication, and the working fluid outlet is isolated, and so that in the re-set position the exhaust outlet and motor port are in communication and the working fluid inlet and the working fluid outlet are in communication; header means having actuating fluid-admitting and actuating fluid-exhausting means operably connected to each or" said actuating fluid inlets to substantially simultaneously communicate actuating fluid thereto and to substantially simultaneously exhaust actuating fluid therefrom; means for providing Working fluid to the working fluid inlet of the first valve in the series; means for conducting working fluid from each of said Working fluid outlets to said working fluid inlet of the next valve in the series; means for exhausting working fluid operably connected to said working fluid outlet of the last valve in the series; and control means for admitting actuating fluid and working fluid to and exhausting actuating fluid and Working fluid from said valves; whereby each of said valves is actuated substantially simultaneously with the actuating fluid thereafter being exhausted, Working fluid is admitted thereafter to fire each motor in sequence, each valve is re-set in sequence to exhaust its associated motor and to conduct Working fluid to the next valve in the series, and Working fluid is then exhausted from said valves whereafter the cycle can be repeated as directed by said control means.

References Cited UNITED STATES PATENTS 941,426 11/1909 Loudon 92-146 X 1,663,513 3/1928 Howse 91-36 X 1,994,974 3/1935 Wiedrnann 60-97 2,290,479 7/1942 Mercier 91-411 X 2,357,986 9/1944 Wichtermann 137-62566 2,466,041 4/ 1949 Peoples et al. 91-421 2,475,298 7/1949 Sloane 91-411 X 2,486,087 10/1949 Wright 91-411 X 2,619,938 12/1952 Larson et a1. 91-421 X 2,818,881 1/1958 Bonner et a1. 91-36 X 2,913,879 11/1959 Cameron 91-413 X 3,233,525 1/1966 Stacey 91-4l2 3,237,641 3/1966 Audemar 137-62566 MARTIN P. SCHWADRON, Primary Examiner.

I. C. COHEN, Assistant Examiner. 

